I understand the shock of OP, yet that's how the majority of airlines operate outside of USA.@:-)

Other than flights to/from USA and Europe, most non-USA airlines still adhere to IATA weight system. Baggage over weight allowance is charged at 1% per kg of one way first class fare. Since OP is 28kg overweight, 28% of one way first class fare is charged, which should come out to around $2700, depending on exchange rate used. Hence, the rate is high but it follows the rules set by IATA and there is nothing illegal about it. OP, by IATA standard, was undercharged. IATA no longer regulate excess baggage fees, but most non-USA airlines still follow old rules.