Unable to Contact - Left holding for over 25 minutes

I have been trying to get hold of the UPS accounts department to get a copy of a VAT invoice, They constantly put you on hold and never come back to you. I got through to the accounts department twice after holding for ages only to have the phone put down on me without even getting a chance to speak to someone. I asked to speak to the Financial Director and was put on hold yet again after 10 minutes I put the phone down and called again. I was told they were transferring me to the accounts supervisor only to be, yet again, placed on hold. I have phoned in excess of 10 times only to be placed on hold. I have even tried e-mailing. Still no luck. I'm not sure what it takes to get through to this company.