Today I made an offer for an item using ebay balance, which was declined, after this I can't pay with it, receiving message: Unfortunately, you don't have any eBay balance to apply towards this order. Please select a different payment method and try again. Even though I have £220 on this balance.

Don't know of any issues with pc parts, try contacting customer service https://www.ebay.co.uk/help/eua?id=5190 usually best done early to mid morning to get Dublin support