OK, that means that both items are part of the same contract; I just wanted to check.
Before you can think about legally terminating the contract because of the time lapsed, you should first make time 'of the essence'. This will involve contacting the company, preferably by phone (and get the full name of the person/s you speak to) and explain that you want/need the device within, say, seven working days. Explain that the lack of the device is causing you loss and that if, after an eight week delay, they don't deliver a working one in the next week or so, you will be treating the contract at an end and returning all the goods for a full refund. Make it clear that you're doing this because of their breach (which renders your contract with them voidable by you). You will be thus exercising your right to void the agreement.
There's no need to be threatening an action for damages etc., as that's needlessly aggravating, but make it clear that you won't be paying for return postage or associated costs. You are not responsible for economic loss arising out of their breach.
I had this issue with PC world and a new desktop. After 10 days, I went in one morning and asked where it was. I didn't like the answer, and I almost lost my temper and gave them until the end of the week to find me one as I needed it for my business and they were causing me loss. They rang me at 3pm that day, saying they'd sourced one from Leicester. A strange conincidence, that...