@Jermaine *****
if you were in an ED visa, then you would hVe had to report to immigration every 90 days, either in person or by online with your TM30.
If then you wanted to extend, you should have gone to immigration again and then Change that back to a tourist visa for 30 days at the cost of 1900 baht. If you wanted to extend the Ed visa, then you should have a letter of confirmation and the various documents and then be given another year. If you overstayed, you would have been bundled to an exit point and you pay the overstay fine and be asked to leave. I think the person at the immigration may have said the wrong thing and I suggest you check your stamp on your passport again.