I'm writing to letter about Assistant office manager to start from next monday. = I'm writing a letter to the assistant office manager about strating work on Monday. However, I have some problems.
As you know, I recently work worked at my uncle's groceries packing industry.  you remember our interview contents that I gained invaluable experience at there. = I told you that my experience there wasn't enough. Unfortunately, my uncle had to be admitted to a the hospital for an operation. Furthermore, And my aunt asked me to help her because it is a busy time of the year.
I know it is an imposition to you, I would like to delay the job for arranged me two weeks later than planned it.  = I would like to delay the job that has been arranged for me for two weeks.
Let me make one point is that I still want to not only more useful work together, but also gain more useful experience during this time. = I'd still want to work productively while gaining an experience during that time.