Turkcell Doesn't Let Me Switch to a Cheaper Package Despite My Disability Discount

I have been a Turkcell user for years. In July, I called customer service to renew my line 0532 662 ** ** because the commitment expired. I was offered the Star 10 GB package and was told that it would be ₺312 because I had a disability discount. Since I was out of town, I could not examine the packages in detail and I accepted it by trusting the customer representative. Later, I found out that the Mega 10 package was ₺280 without a discount. I called customer service to switch to this package because I thought it would be cheaper with the disability discount. I was told that I could switch during my invoice end period. I called on the invoice expiry date, 23.08.2024, but the customer service said that I could not switch to the Mega 10 package. The criteria didn't fit. When I asked what the criteria were, they told me many things and said that you can look at the Turkcell page if you want. In summary, Turkcell allows you to switch to more expensive packages but does not allow you to switch to a cheaper package. Can there be such a commercial understanding? Don't I have the freedom to switch to the package I want? I am a retired person with a disability report. I do not understand why I am not allowed to switch to a cheaper package. I kindly request that my victimisation be eliminated and your attention.