Can I use an HSBC bank account for a long-term visa application in Thailand?

How many retail bank branches does HSBC have in Thailand?

You are applying for a non OA in your home country. You just need to show the amount in your home country bank, not a Thai bank account.

Accept and except are very different things.

Just contact Thai visa Centre they will get you an account

Would that be the HSBC expat account? You need to have a large income or a large deposit to maintain one of those. If they accept a regular HSBC account a UK address is still neccessary.

Thai embassies will accept any bank account. They don't require a bank account in Thailand because they are not in Thailand.

If you are talking about INSIDE of Thailand, NEVER listen to anything a Thai embassy tells you about immigration inside of Thailand. They are completely different government agencies that know nothing about each other.

If you are talking about a non-immigrant visa extension, the you cannot use an HSBC account, you can ONLY use a Thai bank account in your name only with the required proof of funds inside of Thailand.

If you are talking about a DTV extension, then it be will up to the immigration office you are dealing with. The official DTV extension requirements say you can use a foreign bank account, but there are immigration offices that will not accept that and will only accept a Thai bank account.