Billing dispute with Horizon Achievement Training Group

I've received an email from Linda Moore at Horizon Achievement Training Group offering a partial refund, but I believe I'm entitled to a full refund given the circumstances. The winter coat was clearly defective from the start.

Dear valued customer, Thank you for bringing this matter to our attention. We at Horizon Achievement Training Group take all customer concerns seriously and are committed to ensuring your satisfaction. We have reviewed your complaint regarding our t-shirt and have initiated an internal investigation (Reference: REF-523DF5A6). One of our specialists from our Customer Service will be contacting you within the next 12 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, Thomas Walker Client Support Executive Horizon Achievement Training Group Customer Relations