Hi, I work in software support and have been told for the next 3 weeks I have to support a piece of software that I have never been trained on, have access to test on or had the chance to use. The person who supports it usually, is on holiday and no one else in the company knows the product. I was told 10 minutes before she went on holiday. I am now getting customers contact me asking me to call them up to help them solve issues but obviously I have absolutely no idea. This has left me feeling sick with worry, I am terrified of being put in a position where a customer expects me to do and know stuff I just don't. I have had a few issues lately like this at work, what should I do? I think I may have stress but I do not want to go to the doctors if possible because if I go for another job it may go against me. Please help, I feel really stuck.