Looking for a polite way to deal with hotel. Electric current in tub faucet.?

I'm staying in a weekly hotel a little expensive $240 a week. I'm stuck here the week there is an electric current that gives me a mild shock when I am in the shower and go to turn it off. They sent there guy to look at it he found nothing and knows nothing. They want me to pay $75 for another room and refuse to give me back my money for the week. I told them I don't notice it in the morning but at night my Husband and I both get shocked. So I have wasted a whole day here I am scared to shower and I don't know what to do at this point. Any suggestions? Please!!!