That fare code matches the route and dates you mentioned. I have pasted the VOLUNTARY CHANGES part of the rules here and I find nothing to indicate a change is not allowed. You must call BA for this and they may try and charge you a change fee but since an online change is impossible, this should be waived.
EDIT: I code is available on LAS-LGW on 10th Sept, and the fare DUB-LAS at your ticketing date was identical to DUB-PHX, so although you will require a ticket re-issue, this should be the same price.
Originally Posted by ExpertFlyer
IN THE EVENT OF CHANGES TO TICKETED FLIGHTS
BEFORE DEPARTURE OF JOURNEY AND WITHIN TICKET VALIDITY
CERTAIN DOMESTIC REISSUE PROVISIONS MAY BE OVERRIDDEN
BY THOSE OF BA INTERNATIONAL FARES
NO CHARGE CHARGE HIGHEST FEE OF ALL CHANGED FARE
COMPONENTS - DISCOUNTS APPLY - NO FEE FOR INFANTS W/O
SEAT AND
REPRICE USING FARES IN EFFECT WHEN TKT WAS ISSUED
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. NO CHANGE TO 1ST FARE COMPONENT
2. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
3. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
4. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
5. ANY CARRIER I- FARE FAMILY IS USED
6. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
7. ALL RULE AND BOOKING CODE PROVISIONS ARE MET
8. ADV RES IS MEASURED FROM ORIGINAL TKT DATE TO
DEPARTURE OF PRICING UNIT
OR -
REPRICE USING FARES IN EFFECT WHEN TKT WAS ISSUED
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. NO CHANGE TO 1ST FARE COMPONENT
2. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
3. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
4. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
5. ANY CARRIER FARES ARE USED
6. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
7. NEW TKT HAS EQUAL OR HIGHER VALUE THAN PREVIOUS
TKT
8. ALL RULE AND BOOKING CODE PROVISIONS ARE MET
9. ADV RES IS MEASURED FROM ORIGINAL TKT DATE TO
DEPARTURE OF PRICING UNIT
OR -
REPRICE USING FARES IN EFFECT TODAY
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
2. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
3. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
4. ANY CARRIER I- FARE FAMILY IS USED
5. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
6. ADV RES IS MEASURED FROM REISSUE DATE TO
DEPARTURE OF PRICING UNIT
OR -
REPRICE USING FARES IN EFFECT TODAY
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
2. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
3. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
4. ANY CARRIER FARES ARE USED
5. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
6. NEW TKT HAS EQUAL OR HIGHER VALUE THAN PREVIOUS
TKT
7. ADV RES IS MEASURED FROM REISSUE DATE TO
DEPARTURE OF PRICING UNIT
WHEN CHANGE RESULTS IN LOWER FARE IGNORE RESIDUAL THEN
ADD-COLLECT
ENDORSEMENT BOX - HIGHER NON-REF AMT AND NEW
ENDORSEMENTS.
OR -
BEFORE DEPARTURE OF JOURNEY AND WITHIN TICKET VALIDITY
CERTAIN DOMESTIC REISSUE PROVISIONS MAY BE OVERRIDDEN
BY THOSE OF BA INTERNATIONAL FARES
NO CHARGE CHARGE HIGHEST FEE OF ALL CHANGED FARE
COMPONENTS - DISCOUNTS APPLY - NO FEE FOR INFANTS W/O
SEAT AND
CHANGES NOT PERMITTED/REFUND TKT-ANY REMAINING AMT
WILL APPLY TO NEW TKT
WHEN CHANGE RESULTS IN LOWER FARE IGNORE RESIDUAL THEN
ADD-COLLECT
ENDORSEMENT BOX - HIGHER NON-REF AMT AND NEW
ENDORSEMENTS.
OR -
AFTER DEPARTURE OF JOURNEY AND WITHIN TICKET VALIDITY
CERTAIN DOMESTIC REISSUE PROVISIONS MAY BE OVERRIDDEN
BY THOSE OF BA INTERNATIONAL FARES
NO CHARGE CHARGE HIGHEST FEE OF ALL CHANGED FARE
COMPONENTS - DISCOUNTS APPLY - NO FEE FOR INFANTS W/O
SEAT AND
REPRICE USING FARES IN EFFECT WHEN TKT WAS ISSUED
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
2. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
3. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
4. ANY CARRIER I- FARE FAMILY IS USED
5. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
6. ALL RULE AND BOOKING CODE PROVISIONS ARE MET
7. ADV RES IS MEASURED FROM ORIGINAL TKT DATE TO
DEPARTURE OF PRICING UNIT
OR -
REPRICE USING FARES IN EFFECT WHEN TKT WAS ISSUED
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
2. NO CHANGE TO FARE BREAKS UP TO THE FIRST CHANGED
FARE COMPONENT
3. CHANGE IS BEFORE ORIGINAL SCHEDULED FLIGHT
4. ANY CARRIER FARES ARE USED
5. ANY FARE TYPE EXCEPT EOU/ERU ARE USED
6. NEW TKT HAS EQUAL OR HIGHER VALUE THAN PREVIOUS
TKT
7. ALL RULE AND BOOKING CODE PROVISIONS ARE MET
8. ADV RES IS MEASURED FROM ORIGINAL TKT DATE TO
DEPARTURE OF PRICING UNIT
WHEN CHANGE RESULTS IN LOWER FARE IGNORE RESIDUAL THEN
ADD-COLLECT
ENDORSEMENT BOX - HIGHER NON-REF AMT AND NEW
ENDORSEMENTS.
OR -
AFTER DEPARTURE OF JOURNEY AND WITHIN TICKET VALIDITY
CERTAIN DOMESTIC REISSUE PROVISIONS MAY BE OVERRIDDEN
BY THOSE OF BA INTERNATIONAL FARES
NO CHARGE CHARGE HIGHEST FEE OF ALL CHANGED FARE
COMPONENTS - DISCOUNTS APPLY - NO FEE FOR INFANTS W/O
SEAT AND
CHANGES NOT PERMITTED/REFUND TKT-ANY REMAINING AMT
WILL APPLY TO NEW TKT
WHEN CHANGE RESULTS IN LOWER FARE IGNORE RESIDUAL THEN
ADD-COLLECT
ENDORSEMENT BOX - HIGHER NON-REF AMT AND NEW
ENDORSEMENTS.