Fallacy of the letter-writing MP

So some voters would say, "My MP has been a great help in resolving this issue with the [xyz] department. He wrote a letter and it was sorted."

My questions have been, and always remain:

1. Why was that government department not able to resolve your "problem" until a MP steps in? 
2. What are the civil servants for, except to serve the citizens? If they made a mistake then they should jolly well make a polite apology and make sure things are set right. There should not be a need for a voter to go to an MP to "set things right". 
3. After the MP has written the letter and your problem has been resolved, does this MP then go to his colleague in the party or hassle the relevant Minister to ensure that the same mistake does not recur?

Or, do we condone a sluggish, inefficient civil service just so that it appears that MPs are doing something?

I don't wish to malign all civil servants as I am sure that there are very many very good and efficient civil servants.

But when trouble spots appear, they face an obstacle, an "unusual" set of circumstances occurs and they are lost in their bureaucratic mumbo-jumbo, then they are duty-bound to DO SOMETHING to resolve that.

The last thing they should do is say, "Those are the rules. If you are not happy, go to your MP."

If MPs are always busy writing letters to government departments, that means these departments are inefficient, or uncaring, or both. If things do not get done unless "endorsed" by a MP, something is not right.

The ministers in charge should be taken to task, not be rewarded with huge salaries.

Conversely (just for the sake of argument), if ministers are richly rewarded that means their departments are running well, so logically there is no need for these MPs (because no need to write letters, what), so why do MPs still get the high salaries?

MPs are paid a lot of money. Why waste their time writing to government departments? Is writing letter the only reason we vote for a particular MP? If this is the case, then of course the "personalities" matter.

Thankfully I can write my own letters. So when I vote, I vote for a person who would be my "Member of Parliament", someone who would represent my voice in parliament. Not to write letters on my behalf.

Or pull strings.