Swellendam Traffic department - Questionable fines

I have travelled through Swellendam before and received a traffic fine where I was convinced that I did not exceed the traffic limit. However, I paid the fine. I travelled though Swellendam again on the 16th of October. I took extra care to make sure that I kept within the traffic limits seeing my previous experience. I was contacted this week and informed that I was send a mail with two fines from Swellendam. To put this in perspective, I have travelled almost 4000 km over the past month from Pretoria through Lambertsbay, Cape Town all the way to Port Elizabeth and back and these are the only fines I received. This proofs that I am not someone who speeds. I question Swellendam's Traffic Departments honesty as this is impossible. The only fines I receive ever are from them. My mother and brother had the same issue. My mother wrote them a letter but was just told to pay the fine. There is no way to proof anything. If I was stopped and presented with the fines I could have challenged it.