Uber's Helpdesk Do not Respond

At the beginning of the week I mailed Uber notifying them of ********** trips on my credit card.<br> I got a response from the helpdesk saying they can see they were done on another account and since then have shut the account down.<br> I then responded questioning who would be liable for the amount used on these multiple trips and since then have had no reply.<br> <br> This is completely unacceptable as the total is extremely high and I would like someone to be held accountable.<br> Uber, I hope you respond to this.<br> <br> An unhappy client.