wrong payee due to sponsor error. Who pays the stop fee?
 

seems cut and dried to me, but getting dicked around with some shitty support, so:

sponsor sends check with wrong payee, tell me I need to pay the stop fee, or send it back to the USA from the UK, which is time, effort, and cost on my part. Imo the sponsor needs to either accept that I'll write 'VOID' all over the check, and scan it to them, or pay the stop fee themselves and send a new check.

Agree/disagree?

Why was their a wrong payee on the cheque?

I'm guessing because their accounting department are idiots. Payee was changed in October (10th iirc) 2012, check is dated December 25 2012.

It's their problem and they should fix it without you having to pay a stop fee.