Are banks allowed to do this???

babylissy

i got a management loan with my bank 3yrs ago as i was having difficulty repaying my personal loans and credit card once i had lost my job.I signed up to pay £61 every month.i received a letter from the bank this morning saying i am going top be charged £25 as an additional service charge?? when i phoned them to query this the lady i spoke to said it was the interest on my management loan and i would get it every month???? and always had been???? but i haven't at all!!
I was then told that i also get £5.05 deducted from my account every month that goes toward interest on my loan too??!!
I am in a slight arrears on my loan and am paying these at £7pw.
So when i have added it all up i am actually paying £119.05 a month!!!! surely they cant do this and it should all be squeezed into one payment??
I am a mum of 5 children on benefits and this is a huge amount for me.
Can anyone help me with some advise at all please?? thank-you