Billing Problem

On 7/24/2020 we called customer service and downgraded as our bill had increased significantly. We received a confirmation email of having downgraded our Xfinity service. We just received our next bill that does not reflect our downgraded service. We called customer service and were told that there is no record of having changed our service. We explained that there is a record, we have an email. The customer service agent after placing us on hold several times stated that she could not honor our email confirmation. Please advise on what we need to do to have our email confirmation honored.