Won 100 free spins from Betfair, which turned into 5 free spins when I tried to claim them, which turned into 35 free spins when I went on live chat to complain, which turned into no free spins when I complained further on the phone (I wasn't even actually complaining, more trying to help them figure out why their promotion wasn't working. Eventually I figured out the promo link sent me to the wrong part of the website so it was impossible to qualify for the free spins from the games listed on there)
Gave up trying to explain this to them and settled for the 35 spins that they put back into my account. Only won a few pounds from them in the end.