Every guy, who is trying to outsmart their risk management team, kyc that is done through analysis of computer tracking like iovation, has this problem. Also you did not "deposited 50 eur, took the bonus 50 eur, placed that on spain cup". You had to deposit 50, then place 50, then took the bonus <- that was always their system and I bet they did not change it. So you maybe placed 50, got bonus, bet the bonus immediatelly and redeposited and bet again. And that is not casual bettor behavior, not even close. And that is why you got limit. Use the thing that grows from your neck.
I do not expect you will tell here who you are, you just want to make pressure on Bet365. If you want to do it, fine. But not in so stupid way as you are trying to grab their bonuses or beat their weak lines.
If you talk to God, you are praying; If God talks to you, you have schizophrenia.