If X or [if] Y - Should I extend conditional after "or"?

Question

I have a message to write where the recipient may encounter two problems. It is currently written like this:

"If you are having problem X or if you are having problem Y please contact Z."

I'm not sure if the second if is necessary or even allowed.

Should it be:

"If you are having problem X or you are having problem Y please contact Z."

Or even:

"If you are having problem X or problem Y please contact Z."

English isn't my primary language so I was hoping to get an answer here for the proper wording.

The criteria is the clearest and easiest to read message (which is proper English) wins.

Answer 1

The first statement you suggested is fine, but as you noted, it isn't the shortest nor smoothest sentence.

Given that there are only two problems and only one suggested action, there is not a lot of ambiguity in the last formulation:

If you are having problem X or problem Y please contact Z.

However, the clarity of the sentence depends heavily on how the problems are worded! If the problem statements are very long, it might be good to start over with a new "if". For instance

If you have problems restarting your computer or configuring your router, then call our tech support

is very readable, whilst

If you are having problems restarting your computer due to the power button being stuck and the computer being too small for you hands, or opening the window, then please call our tech support

is a rather obnoxious statement.

Also, when you are using different formulations*, an extra "if" is essential:

If you are having problems opening your door, or if you are unable to find your keys, please contact the police

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*As mentioned in the comments below, this is not quite precise enough. When using several different verb phrases, you need to separate them and using an extra 'if' can help with that.