Renting property in Thailand - will I have to pay for damages to furniture if it wasn't my fault ?

I live in a furnished apartment in Chiang Mai, Thailand (not the luxury type). Two days ago, I was sitting in front of my laptop on a provided chair (5 steel legs with wheels) while talking to a friend on Skype (PC call). One of the 5 steel legs suddenly bended, the chair fell backward and the backside of my head hit the floor. Next day I talked to the apartment office to replace the damaged chair with a wooden 4-leg steady chair. But they want me to pay for the damaged 5-leg chair. The way I see it:

a. The damaged chair is an old chair. Since the apartment complex is 8 to 9 years old. Who knows how many residents have used (even abused) this chair before. Why should I pay the offce the price of a new chair?

b. There is no way a new resident being an expert on metal fatigue and having the necessary equipment to X-ray examine whether the chair leg has reached the yielding point while checking in, and demanding a new chair (dream on -- the office will never give a new chair)

c. After inspection, it reveals that the chair legs are made of "thin" steel, not to the standard of Europe or USA. And that is most likely why one of the chair leg yielded while I was just sitting on the chair talking to my friend over Skype.

d. Since the office claims that I damaged their property, shouldn't it also reasonable that they are responsible for my head injury if there is any (I have not done any CAT scan in a hospttal so far to verify if there is any permanent injury to my head which could appear several weeks later) since the "dangerous" chair is provided by them?

I understand that this is Thailand, and many Western standard rules do not apply here. Could anyone please give an advise what I could do at this point?