Paying for a system no longer in use

My husband bought a new car and sold his old car, and we informed Tracker of this. Because the system in our old car was older than 2 years they indicated that we must start a new contract and install a new system. With the new system (because we are with MiWay) we are suppose to pay R75. I checked my bank statement today and noticed that R245.67 was deducted from my account. When my husband phone they informed him that he has to pay a month cancellation fee on the old system and now pay for the new system as well. Now my maths might not be that great, however, R105.01 (old contract) with R75 new contract does not equal R245.67. I also feel that we have been loyal customers for over 5 years (both me and my husband have tracker systems in our cars) with tracker and to double charge us for a system that is no longer in use, is just bad customer service, and I regret making use of them again.