No signal, so want to end contract & return phone

joined ID Mobile in April, and despite checking on line the network coverage map assuring me I had a good signal I found that I was unable to use my phone for voice or data in the house and really outside. I knew I would be moving house so waited till the move in July after checking the coverage map which promised a good signal.
I have lived at my new address since July 2019 TN33 0.. and I have not been able to use my phone. I have no signal in the house again and hardly ever outside. Despite the coverage checker telling me I have a god signal.
I notice that there is a disclaimer on the coverage checker 'Although we try to make these coverage results as accurate as possible, the information is only a guide and doesn't guarantee service availability in a particular location.'
So it is made clear that there is no guarantee of service availability despite the online map.
I have spent half an hour talking to an adviser today and now have to wait 3-5 business days for a manager to get back to me.
I have been paying for a service from ID for over 5 months and faced with the remainder of a two year contract for a service I cannot use. The ID App says that the ID Network want to make it easy for people to end their contract if necessary, but I have found that I will be charged £466 to end the contract. My view is that if ID cannot provide the service I am paying for and state they cannot guarantee it then I should be able to return the mobile phone and call it a day.
I have a Google Pixel 3 which is in Pristine condition as it is in a hybrid case with a screen protector and I have the box and all the accessories. If ID were to cancel the contract and take back the phone they would be able to reissue it without any problems.
I spent two years on the EE Network with the same issues and cannot go through that again. They had a supposed WIFI calling back up using my broadband service but it never worked and was a nightmare. I paid for two years for a service I could not use.
My wife and daughter are both on Vodafone and are able to use their phones without any problems in either house and local area so it is definitely a network coverage issue. My son's Tesco Sim (02) works as well.
I really need to be able to use the Mobile for personal and work use and to be contactable, which I won't go into.
The adviser took me through the MPN settings on the phone which is set up correctly and just went by what the map was saying. I now have to wait 3-5 business days for a manager to get back to me but I am not holding my breath. I kept repeating that if they look through my last 5 months of bills that there is hardly any use on there whatsoever, due to the fact I cannot use the service. My Pixel 3 is reduced to being usable only on WiFi as a small tablet which defeats the object and purpose of a mobile phone.
Sorry for the long thread but I would welcome advice or action on what to do next. I cannot see ID resolving this issue and providing me with the service I am paying for and I am not willing to pay off a contract which is not being fulfilled by ID.
I am very happy to return the Pixel 3 with all accessories and box etc call it a day and go to Vodfone who's network does work here. If I cannot do that then is there another avenue such as Ofcom, Trading Standards, Martin Lewis at Money Supermarket.com

How have others resolved the issue?

Thanks for reading and hopefully contributing