Bad service

I was quoted and sent an invoice to pay after paying apparently the stock taking guys made a mistake on pricing and it took them a week to figure it out ....now that the engine need to picked up they asked me to pay an extra 10k for me to get it I'm literally been punished for their negligence and they want to take responsibility...the only thing their manager can say was I'm sorry we not gonna loose money so we can refund...what an inconvenience cause ...people be careful of such business that are selfish and taking advantage of their customers.