Right.
I am currently going through this, with a company not far away from the op.
I cant say much at the moment, suffice to say your first port of call HAS to be ACAS, then if no amicable solution is forthcoming, then a tribunal is thereafter.
On the subject of deductions.
Other than the statutory ones in law, (Tax and NI) your employer cannot deduct any monies without your express agreement. Period.
Ken.