Remember the 7 days is 7
working days. i.e. excludes weekends and bank holidays.
And that countdown starts the day
after you take delivery.
So what's the the 21st? The day it was ordered, or the day it was delivered. If so, count 7
working days, and if within it, notify the cancellation
in some permanent form, not by phone, within that period.
This is assuming it was a distance purchase, of course, not something you bought in a shop in person.
Otherwise, the
seller is liable for goods that fail to meet the Sale of Goods Act duties, such as satisfactory quality, for
up to 6 years. If you find a fault, the question is, did the fault exist when you bought the product, or is it down to something you've done
since? If it existed when you bought it, the seller is liable. If it's something you've done (inappropriate use, dropped in and damaged it, etc) then they aren't.
For 6
months after purchase, the presumption by law is that the item was faulty when sold, unless the seller can prove it was not. And that certainly still applies.
It can get a bit more complex with mobile phones if the "ship" is just an agent for the network, and that 7 day period can be curtailed in the event of services that have commenced before that time, with your permission.
Were it me, I'd be back at the seller, pointing out "7 WORKING days starting the day after delivery", and see what they say next. In any event, get that to them in writing (fax, email, letter, etc) ASAP if you intend to rely on it because phone conversations
do not count (usually), and if you let that 7 working days expire, then any DSR rights are gone.
And if they keep on with this "talk to the manufacturer", talk to Trading Standards and/or Consumer direct. If the shop is trying to lie it's way put of it's legal obligations, TS have a habit of prosecuting.
(Note) In case anyone is going to point it out, it might be a lot longer than 7 working days, if the seller has not provided information they MUST provide. Few screw up like that any more, so it''s rare for it to apply. But it could be up to 3 months and 7 working days, as a maximum.