Might be clutching at straws but when and how did you buy the scope? From what I've read it, if it was an online transaction then distance selling regs say you have 14 days to tell them you want to return goods even if it's not faulty and no obligation to provide a reason for returning it. Otherwise it would be dependent on the suppliers good will return policy or item is faulty or doesn't do what it is supposed to do - which seems to be in dispute. https://www.gov.uk/accepting-returns-and-giving-refunds If you're not eligible for a refund I would be tempted to have Tak re-certify it. They might find and correct something when taking a closer look at it.