i recently purchased a secondhand pc tower from cash generator after getting it home it shut down after a few days i returned it to the shop and they said they had fixed it i got it home only to find 2 drivers were not on the tower for audio and dvd. i returned it again left it there for a day .my partner went to collect the tower and they charged her £25. they did not advise us of this charge when we returned the tower.the tower came with a 3 month warranty. do i have to pay this bill.