Can I switch companies after obtaining a work visa in Thailand during the initial three-month period?

Hi everyone I need some advice. I got my work visa for company A for three months by leaving the country. I then got my 6 month work permit for company A after coming back to Thailand. Company A recently opened company B for digital services ( different scope than company A) and moved me and my work permit to company B. My work permit now has company B and removed company A. I wanted to apply for visa extension and the lawyer said I wasn’t allowed to switch companies in the first three months and the extension will have to be with the company that I got my visa for (company A). Is this true? I thought you can switch companies during the first three months with the visa since it’s not an extension but an actual visa