Denied payrise

I'm currently on 12 pound an hour which is currently more than minimum wage until April. I've been doing more than my contract and assumed I would get more in April but apparently I will be getting minimum wage. I arranged a meeting about it which was suppose to be next week but they decided to do it today even though I said i wasnt ready. I got picked on massively and basically got told I'm not a good enough chef ect but then they turned round and said I'am right for the job which makes no sense as they said i wasn't good enough for the pay rise. What also doesnt add up is im currently on more money than anyone else there but next month i will be on the same as them and Im the only one who does the kitchen and front of house and opening and closing. In mylife I've been told that i was never good enough. Can't stop crying. Rant over