How to estimate amount of work/man hours for an unfamiliar task? This project is fixed bid project from customer. And most of our project is fixed bid project, for the past 3 - 4 project we are running at lost because we never have a so call fixed loyal customer and the technology base will keep changing due to different customer. Therefore, we always run into 2 condition: 1) angry customer which want to uncut our cost but in long run it burns our pocket. 2) Hiring 3rd parties vendor which we don't have technical knowledge to verify their delivery, most of the time all the issue and bug will appear during the closing phase. Endup we need to switch vendor, but in long run....due to different technology needs for different product we were not able to procurement the right vendor to do the task.
If a task is unfamiliar to you, hire or partner with someone who is familiar with the task or don't bid. If you have a lot of uncertainty in the task, bid it T&M or load a ton of contingency in your fixed price, or don't bid. If requirements change with a change in customer and you don't have a change management process to reprice the changes, then don't bid.
You exposed a lot of internal capability maturity issues in your post. Notwithstanding this current bid, you need to focus internally and mature your processes. If your firm wishes to continue to go after unfamiliar tasks, and you cannot vet your vendors adequately, the solution is simple: do not bid FFP. If FFP is required, walk away.