Unfairly charged for towing

On 15 June I requested roadside assistance from Tracker. The lady who was assisting me said to me that I will only be charged if the distance to where the car is being towed is more than 30KM. Since it was not, I continued with the process. And I was assisted, the car towed to a mechanic. From Pretoria West to CBD. Which is well under 10KM. To my surprise today I get an sms that I will be paying R400 or so on top of my normal monthly payment. I called to enquire, was told that they charge if the distance travelled by the towing truck to my car and to the drop off (mechanic) is over 40KM. And I am positive that they could’ve found a tow truck in the vicinity. But anyway, this was not communicated to me beforehand, otherwise I would’ve opted for my insurance which is free. I feel I am being charged unfairly and I’m quite disheartened.