Hello,
last year I entered on an e-visa from London and found, when I arrived at Suvarnabhumi, that the passport number on the visa was incorrect by one numeral. I was taken to one side and the mistake was corrected and entered into a computer. I was assured that all would be well.
Having checked my visa application I saw that the error had been made by the embassy but, as with you, they declined to give any assistance or correction when I contacted them.
Predictably, when I went to CW to extend the visa, it was refused.
Later, I returned to London but then found out that there is an office in Bangkok dedicated to correcting errors on visas. I think it’s near CW and someone on here will have the address. One might think that those in this situation would be directed to this office by officers at CW, but that would be wishful thinking!
When I applied, this year for a non-O multi entry, I went through the visa with a fine tooth comb. A lesson learned!
Hope you can get it sorted.