Drying me out of money

i have been with the company for two years and i have a big problem. the company used to deduct late in our account and they promised to fixed it, till they decided they will deduct double in our account and find that we didnt budget for that amount meaning the arreas will increase, they will not inform us before they deduct or sent us statement before head to warn us. we will only find the information when we call them. we managed from june last year to settle all the remaining amount and change the deduction date. the problem now become that we were told of other arrears that we were not aware of and when i saw that they didn't deduct in october i called to check why only to be told that they tried to deduct more than agreed monthly amount and it returend back to them again, so i was told i had arrears and i paid them in December. now we sold our car and we didn't need a tracker and told them that we will like to cancel and i was told on the 17th that is ok and there will be no charges. now they came back late December to say am in arrears, i called to check and they said i also have to pay settlement fee i was not made aware of. all they have done is taking from us without servi