Yes, I thought we could combine FFC s, but I was told by multiple reps and a super that only one FFC (or ETc, obviously) can be used per booking.

My background : I live in Canada, I always book UA to international destinations outside of US/CA.

As most of the time, I found a fare on Google flights (GF), but if I searched on United.com, the fare wouldn't show. I would call them with Cart ID to book, but sometime last year, I was told by multiple reps that they can't pull up itineraries with Cart ID. I thought I had to book online and apply those FFC by myself.

I had 3 credits, in order of large amount to small, all under my name:

1. A refundable CA to US ticket in CAD that I speculatively bought when there was an Amex offer. The change flight function doesn't show the fare I found on GF, so I changed it to a slightly more expensive non refundable ticket. After 25 hours, I cancelled it to produce a FFC.

2. A compensation etc USD 150 when my seat was missing the tray table, and it was proactively given to me at the gate before boarding! As I understood etc cannot be used with FFC, so I bought a slightly more expensive non refundable CA to US ticket, after 25 hours, I cancelled it to produce the second FFC.

3. I used travelbank to buy a slightly more expensive non refundable US domestic ticket. After 25 hours, I cancelled it to produce the 3rd FFC.

When I went to click through from GF to buy a ticket from CA to S America, at payment page, it allowed me to redeem #3 only. #1 and #2, the only option was to ‘change’ flights, as if they were active bookings. I tried on both CA and US sites. When I tried to ‘change' flights, of course it didn't give me the itinerary I found on GF.

I thought I could call UA to combine 3 into 1.

I called UA, the rep couldn't combine them, so she called her super to take over, I waited for half an hour. The super told me he couldn't combine them, because I added some CAD with CC for #1 and #2. He was adamant that I need to make 3 bookings in order to use up all 3, he couldn't combine them.

Before I know it, he ended up converting the USD FFC #3 into an etc. I still don't understand why he did it, because 2 of the credits were in cad or added some CAD.

After I tried by myself to apply them online, I called back, another rep tried to apply all or 2 of them, no success. He also thinks only 1 FFC or 1 etc can be applied per booking. The ticket is for S America, so buying 2 one way was a lot more expensive.

He also said he couldn't combine all 3 or 2 into one FFC.

He noticed that #1 was originally a refundable ticket, he asked me why I changed it to a non refundable ticket. I explained him that I thought I could redeem multiple FFC at checkout, so I converted to an FFC, and I didn't have to rely on change flight function. He thinks that I'm still eligible for a refund the refundable portion to the Amex, then the additional amount I paid with different card to buy a non refundable ticket to be probably issued as (yet another!) FFC. He told me to fill out the form on united.com/refunds. I ended up buying a ticket with the credit #2 with him. He tried every possible combinations, but he came to a conclusion that only 1 FFC or ETc can be used per booking.

So I wonder if paying with multiple FFC only works if original tickets were all US domestic and in USD. I hate such restrictions, because if FFC was to be redeemed one per booking, it can be used with any currencies the booking is based on.