where do i stand in regards to uncollected faulty item from online purchase?

[Tortoise]

Received faulty bike from sports direct. Phoned them, sorted collection, they failed to collect. Phoned again that day, arranged collection for another day. Again, waited in all day for collection, failed to turn up again. Yet again, I phoned complaining about non collection. They said would refund and re-arranged collection for today.
So, I wait in all day again (lovely day in half term could have taken dc out), and no van turned up!
So, I refuse to waste my phone bill yet again to sort this out. I have my money back so I don't care about that.
Where do I stand in regards with them not collecting? Do I have to contact again or is it now their problem? What if it is still here in a weeks time? Or longer?

[OldLadyKnowsNothing]

I think that after 6 months the item becomes yours, but I'm not sure; that may apply only to unsolicited goods. Write to them and say that if they haven't collected by X date (X being 6 mo after delivery) you will dispose of the faulty machine. They should be collecting at your conveience anyway.

[Collaborate]

There is an act covering this. Can't recall the name, but you'll never own it. You can serve them notice to collect and sell if they don't but then must account to them for the proceeds.