I think this will be the route I will take and get a new Visa this coming winter which will then need extending each year when i plan to be present in Thailand. Thanks everyone for your replies 👍
To answer your question (which others have misunderstood), there seems very little QA on products sold compared to Europe and Scandanavia. I lived in the USA and was suprised at some of the substandard products sold in big stores but Thailand has very loose controls for standards it seems.
As said above, you need the 800k in your bank for 2 months before and 3 months after and even after the 3 months is up it must never fall below 400k.
You need a bank statement showing that the money came from outside Thailand, a letter from your bank confirming the ammount in your bank on the day of application and a bank statement printed and dated on the day of application also plus all your other paperwork for rental lease, pasdport copies, etc etc.....
4 weeks seems long to keep your passport but on getting the visa it is stamped as 'under consideration' and they will give you a date to return to immigration for the actual visa stamp so maybe the agent just finds it easier to keep the passport for this period. You dont need an agent by the way but it can make it easier.