Please check

As your writing improves, it becomes more difficult to just point you toward an issue without also discussing the possible correction. 

"called up" is correct and appropriate for a conversational style.  However, the "up" is not needed and "called" can be used alone without changing the meaning. You could also say "rang up" or just "rang".

The style manuals and experts disagree on the next item. Some say you should place a comma between "friend" and "Sandeep".  Others say if there is no possibility of confusion, then no comma is fine. for your sentence, I would leave the comma out -- unless you want to emphasis a slight pause there.

The opening cluase of the sentence sentence sounds a bit awkward -- "after having" makes me think it can't decide whether it wants to be a prepositional introductory phrase or a gerund phrase.  Your sentence would be stronger if it were one or the other.

I'm not sure how to express this next idea. "anyway" is often used as a synonym for "in any case" or "in any event".  However, you need a contrasting thought to balance the "anyway".  (Sorry, I'm really drawing a blank on how to express the idea. Perhaps I'll come back or somebody else will jump in.)

The last sentence is not a compound so the semi colon is incorrect.