Hello! It's great that you want to get back into work and in turn that will help your anxiety to.
Sorry to hear about your last interviews but at least be proud of yourself that you went to them instead of shying away as that's progress!
I don't know how to help you with completely solving the social anxiety as that's quite personal and will most likely only improve with constant exposure, but have you tried some off the counter remedies like rescue remedy, calms, and there's a whole shelf in boots. Just make sure you have a mint if you use liquid rescue remedy because it makes your breathe smell like alcohol!
Depending on what the job is could you also phone in advance and inform them of your issue and just be really honest about it?
On the interview side, its really good to bring a notepad and write beforehand key things you want to mention so you don't go blank and you don't waffle on and then afterwards think oops I didn't mention any of this.
I like to write down some really risky questions to like "how would your staff describe you as a manager" it always throws them but you want to gauge what type of person they are before asking these so have a bunch of questions written down on separate pages and bookmark them. Just tailor your notes to the company style.
Bring multiple copies of your cv to in a folder so you can provide each interviewer with a copy. Even if they have it already it shows a high level of organisation. You can also mention with the note pad "I hope it's ok I brought this notepad as I love being organised and writing things down"
I really hope it goes well for you and try not to worry to much leading up to the interview, they liked you enough on the phone to want to meet you so that's great.