Call out costs on company failed unit

I had Tracker fitted to 2 vehicles - 1 in 2011 and the other in 2014. Terms and conditions cover the company for poor service in testing of the tracking unit stating that if they do not test the unit then the onus is on the owner to call in for the test to be done. Disappointingly, this is the process that I have been subjected to where one of the vehicles failed the test only after I called in for it to be checked. Despite the test being conducted on the 20th February 2015, I was not informed that the unit failed. The warranty on their unit only lasts for 12 months, and any failure of the unit after warranty is for the owners account, who is also liable for a technician call out fee. The sad part is that the manager could not sufficiently justify the reasons for the monthly instalment and only reverted to the contract terms. Even more concerning is that had my vehicle been ****** the claim could be repudiated by my insurance. I feel that Tracker has found a way to absolve themselves from all the responsibility they have as a service provider.