T's & C's contradicts online system functionality, refuses to honor system functionality

I recently found insurance for a much better rate at a different insurance company.

I go ahead and request the cancellation of my entire policy at Miway online, which is great that I can do this without having to call anyone. Now my policy at the new company is set to start on the 15th of October 2018 and great because I can select any date as the date of cancellation with my Miway online, happy.

A few days later a Miway consultant phones me and informs me that I can only cancel my policy on the 7th of November 2018... Now, why let me select a date of 15 October 2018 when cancelling online?

The other insurance company that I cancelled a policy with accepted by cancellation date even though I had to email them and informed me that they will be refunding me pro rata as the debit order was already processed... Now this is customer service.

I've had insurance with Miway for over 6 years, but due to this I will not consider them again in the future!

How can your systems provide functionality that contradicts your T's & C's?