Ticket route:
1.MCT-Frankfurt WY carrier, Frankfurt-TPA Lufthansa carrier
2.DAY-IAD UA carrier , IAD-LHR UA carrier, LHR-MCT WY carrier

My issue when traveling on route 2 while checking our luggage the UA counter refused to transfer our luggage all the way to our final destination. His reason was that they don't transfer to Oman because WY is not an alliance!!!
Note :we had excess baggage and paid $600 for it to UA
When reaching LHR we went through terminals and immigration and collected our luggage again and had to wait for 10 hours to recheck our bags. (we had 14 hrs layover in LHR)
When rechecking our luggage at WY they were surprised why our luggage was not transfered to our final destination according to them UA and WY have an agreement
Note:again I had to pay 300 Gbp = $380
I complained officially to UA and their final settlemt was to reimburse me for only $400.
There justification is that if there more than 4hr layover they don't transfer luggage!!!!!
Note: We bought Business class tickets because of the long layover and long flight
My question is :Is there anything written that says if layover more than 4hrs in international flights UA doesn't transfer luggage to final destination?
And is there anything I can do to get a compinsation for the hardship in LHR??

Thanks
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