moving goal post to suit them

took out a policy for my car &house hold they have been gladly taking their premiums for almost a year in this time they send email stating if you have a accident and is not your fault they excess would be waved some one rear ended me on the 14th august I put in a claim that was all sorted out perfectly but when I referred back to the email sent to about the excess to be waved I was told no I don't qualify because I don't have some monitoring device fitted by discovery insure what ****es me off at no stage on selling me the policy wasnt told of this monitoring device was told about fuel spend now all of sudden I get told about this , now you do things just to suit you no difference from any other insurer bunch of duckers and divers come on guys start standing by your statements