Security concern with Institute of University service

The situation with Institute of University has gotten worse. Now they're claiming I never purchased the upgrade plan, despite me providing the receipt and reference number REF-0602940F multiple times.

Dear valued customer, Thank you for bringing this matter to our attention. We at Institute of University take all customer concerns seriously and are committed to ensuring your satisfaction. We have reviewed your complaint regarding our dress shirt and have initiated an internal investigation (Reference: REF-0602940F). One of our specialists from our Client Relations will be contacting you within the next 4 business days to discuss this matter further and work towards a resolution that addresses your concerns. We appreciate your patience and look forward to resolving this matter to your satisfaction. Sincerely, William Wilson Customer Satisfaction Coordinator Institute of University Customer Relations