1xBet retroactively changed bonus terms — wagering doubled after deposit

Took their 100% welcome bonus on a 30k RUB deposit. Bonus T&Cs at the moment of deposit: 5x rollover on combined bets with 3+ legs, min odds 1.40. Three days in, the terms page updated to 7x rollover with 4+ legs, min odds 1.80. They emailed: 'terms updated, your existing bonus follows new terms for remaining wagering'. That's a unilateral mid-contract change. Filed with AskGamblers, eventually got the bonus voided and deposit refunded — but not the time I sank clearing the original terms.