Incorrect amounts debited

In July I did an upgrade I only took a sim, monthly instalment R200.00

On the 1st of August they debited two amount R75.00 and R438.00. I didn't understand but I thought its pro rata as it was an upgrade.

On the 1st of September they debited three different amounts R75.00 and R438.00.

I went to MTN Ghandi Square the guy that was assisting me he said, its pro rata charges, instalment and insurance.

I thought when I took Sim card only the insurance will be cancelled automatically, but it didn't. I called after I left the shop to cancel the insurance.

They debited again R237.00 of which I don't know why.

Can I have my money back please and I want to cancel the debit order.

I signed the contract for R200 only not more than that