Hi Olcay,
Sorry for the inconvenience caused by the issue.
According to the information you’ve provided, there could be something wrong with the purchase service in your Office 365 subscription. Since the issue is related to sales and billing, to solve the issue more quickly, I suggest you contact our Billing Support team directly via Phone Support (you can get the local support phone number by selecting the region in the page), thus, our support will assist you closely to get the issue resolved.