I work at a small (8-10 employees) company. Since January, one of our tech engineers has been absent due to disability. The other tech engineer had handed in his notice and left in February. Now, a lot of our customers have been waiting for weeks for their scheduled maintenance and projects to be finished.
This work consists mostly of industrial printer maintenance, windows server environments and networking. My boss seems to believe that I come from a similar background, having worked in a local computer store (fixing computers and reinstalling windows). I'm currently employed here as a software engineer, which is where my real qualifications and skills lie.
Because I'm the only one in the company who has skills even remotely close to the work that needs to be done, and we're having serious issues finding replacements for our tech engineers, I've been asked to take on some tasks. At first, I didn't really mind and I didn't want to say no. However, this has been going on for some weeks now on top of my regular tasks. The work has gotten increasingly difficult with more and more responsibility.
Customers are somewhat understanding - especially the regulars, who know of the situation. I still feel extremely uncomfortable going in with limited knowledge, trying to figure everything out on the spot and making a lot of mistakes in the process.
How can I approach my boss to avoid this turning into a more permanent or long-term thing? We're a pretty informal company, but my boss is a typical "everything is possible" boss and won't take no for an answer.