Medication payment

I’ve sent several emails to Medipost regarding the money they say I owe them. My medication is R270 which I pay every month in December 2025 they did have the brand of medication I use they gave me cheaper one which is R189. Meaning they owe me balance, and February I pressed with R181 to balance R270 since they owe me, again they couriered cheaper medication and I’ve mentioned to them to send me medication that’s on my prescription hence I’m paying R270. I keep on getting messages from them saying I owe them, and they’re the ones owing me. I’ve sent several emails to their different departments but no one is getting back to me. I have proof of payments.