Wages

hi , ive been in this salon for 4 years and i have not had a pay rise for 2 years i am a fully qualyfied stylist i am 20 and i am more like a manager in the shop i have the responsibility of opening and closing shop banking mopney tilling up money stock takings and all other around jobs plus my boss seems to this that i have to still shampoo and run about after her i no she is paying me a set wage and i dont mind helping out but it realy does take the p*** sumtimes i am on a set wage of 180 pound a week and she has promised a payrise of 250 a week i asked her not long and she says she hopes she can giv it me its like she always tells me things are going to happen and they never do and it puts me down what advice can u give me on this matter its making me feel like im doing everything for her and not getting anything in return just aload of rubish said please help!!!! x thankyou