3 won't help me return my router

[Makeitstop]

I signed up for the 4G home broadband on March 1st, the HUB & sim were delivered the next day & I immediately decided to cancel. It just wasn't right for me & not really fast enough for a 24 month contract. So I went on the live chat & rang & I kept getting cut off after 29 minutes, I now realise I was being cut off because of a fault between Xperia and Vodafone so not 3's fault. Anyway I finally got through & managed to cancel on Friday March 3rd. I chose to wait for a jiffy bag to return the router. 2 weeks later, 17/03/23, it still hadn't arrived so I called again. They said I would be emailed a DPD label in 16 working hours, by Tuesday because of the weekend, that never arrived. Thursday 23/03/23 I called again & they said they would send me another label the next business day. Well I still don't have it.

I don't know what to do now, I've already wasted over 5 hours on the phone & have gotten nowhere. I have one week before my 30 days are up & still have no way of returning it. I can't even send it myself since I have no address to send it to. Any help/advice would be appreciated. Anyone know what happens if you don't return within 30 days?  

[Anvil_Iron]

There's an address on the cancellation form on this page. Quote any returns order number if you have one.

https://www.three.co.uk/terms-conditions/returns-and-exchange-policy?intid=contactus-link

[sc1999]

Some live chats allow you to print out the conversation; does 3's? If it does have another conversation and print out the conversation so you should be covered if 3 says you had to return the router in 30 days.

[Gary501]

That doesn’t work because 3 never replied to me. 6 phone calls and 2 letters later still nothing. 
3 your service is rubbish.