Hi there .
Okay , so there are two types of system , one is lucas ( square fob ) and Pectron ( oval fobs ) so it depends on which one you have .
I had the very same issue with my TF with a Pectron bcu and fobs . I believe, although some may disagree that the system works on a rolling code and that due to poor range of the transmitter, when attempting to disarm the system by repeated pressing of the unlock button , this rolls the code passed a point where the system can cope . Of course it may be that the fob buttons are faulty and these I think can be purchased from Flea Bay. If you contact Paul Brown ( Technozen ) who is a wizard with everything to do with both systems ( Lucas and Pectron ) he will sort the problem but you will have to send him the fobs and the bcu .
John