Seagate 1TB external hard drive

Purchased a Seagate 1TB Slip eternal hard drive 7 August 2017 at DionWired Woodmead Retail Park. Used it 4 times successfully. Tried using 1 November 2017 not working. ? Did all necessary troubleshooting. Store advised will need to be repaired. Told them there is very confidential information stored and no way will I hand it over. Palesa got back to me to say that it needs to be processed through the store takes 3 weeks. Spoke to Admin Manager who said I could take it directly to the supplier but would find out first and call back. 3 hours later no contact!