Vodafone's Unjust Internet Usage Claims

I'm a Vodafone postpaid customer with a $54 monthly package. My plan only includes internet access, which justifies the price. However, I recently encountered a strange problem. When I briefly turned on mobile data, I received notifications that I had used up 80% of my data allowance. Normally, I pay around $60 per month, but this time I received a bill for 593 tl. When I contacted customer service, they informed me that I had exceeded my internet limit. I work at a company that provides internet access, and I have internet at home, so the constant accusation of overage doesn't add up. Even if I had gone over my credit limit, how did my bill go from 60 tl to 593 tl? This charge is completely unacceptable to me. It's ridiculous that enabling and disabling mobile data results in a 593 tl bill. I've never left my mobile data on all the time. I demand that my refund request be approved as soon as possible.