Id like to try and bust a few myths and clarify some of the issues in a hopefully balanced way. I lead teams that support vulnerable customers in this sector so will try to provide a balanced view.
As others have mentioned smart meters being fitted now are smets 2 Meters which will work with any supplier and you can change supplier at the end of your current tariff as normal.
Smart meters do not lead to higher bills/higher consumption. Your unit prices remain the same. What is does mean is your bills become more accurate and are not based on estimates. This can mean that the initial bill post meter installation could lead to a higher direct debit/debt balance initially if you haven't provided actual readings recently and your consumption is higher than expected vs your previously estimated bills. The frequency of smart meter readings will however prevent bill shock in future.
Non communicating smart meters can occasionally happen where the signal is weak, thick walls, distance is a factor. In this scenario you continue to provide manual readings by pressing a couple of buttons or by having your meter read as with a traditional dumb meter. You don't get the benefits of accurate actual bills every month and ability to view your consumption. This is more likely to happen in very old or rural properties.
A communicating smart meter can be changed from credit to prepayment mode remotely by the supplier. Ofgem have rightly put rules in place that mean suppliers have a very high bar to reach before they can do this and only if it is 'safe and practical' to do so. If you have a traditional prepayment meter, smart is much more convenient as top ups can be done via phone app rather than traditional key/card.
Suppliers have an obligation to roll out this technology and can be fined for not doing so.
My personal experience was that pureplanet couldn't fit smart at first attempt due to my gas pipework into a 100yr old semi needing upgrading. The contacted the distributer who then completed the work. The smart meter was then fitted by Shell and I'm now supplied by Octopus. The data about my consumption I can access has given me insight to what times of day I was being wasteful and I've been able to reduce my consumption over winter in particular by 10% or so cushioning me from the worst of the price increases.
If you are a financially stable credit customer, or an existing prepay customer without a debt recovery rate applied to your meter there's more pros than risks to having one fitted in my experience.