Amazon MarketPlace sellers are not Amazon, and Amazon have a rule that you should try to get redress from the seller, before Amazon becomes involved. Amazon will not refund, but usually contact the seller on your behalf.
eBay have a total different way of dealing with disputes.
There are quite a number of people using the title of PC Supplies, so taking into consideration what you have stated, perhaps this is a one-person band outfit, hence telephone unanswered and away on holiday.
The problem with buying these cheap software offers, is that they are usually items that should have been supplied with a machine, clearance or copies.
Sorry that I cannot offer further advice, but it looks like waiting for a response from the seller. At least your email would be available from Amazon and your account, if the seller doesn't resolve the issues.