PnP online overcharges credit cards

I ordered from PnP online, and was charged R1006.82 on my credit card. On delivery 3 items were not delivered, yet I was charged for all three. They overcharged my card with R289.97. When I phoned, they said they will refund one item of R89.99 however the remaining balance of R199.98 I need to sort out with my bank, due to these items reflecting as “not delivered” on my invoice. The manager kept saying they wont charge for items not delivered, yet the amount of the said items are exactly what is overcharged. Apparently they always overcharge in case they need extra packets. Funny since I dont get my stuff delivered in packets. And seriously R200 packets for R1000 groceries!??? I find this utterly rediculous. The procedures with banks are tedious when transactions are being disputed. Will never use PnP online again and recommend to readers not to use them either!