[have been pranked] or [was pranked] or [am pranked]

I have made up the two sentences below.

(1a) I have been pranked quite a few times when I am working at Max Realty.

(1b) I was pranked quite a few times when I was working at Max Realty.

---------------------------------------------------------------------------

My non-native English speaking friends think the tenses are wrong, so they have revised them to make the sentence below.

(1c) I have been pranked quite a few times when I was working at Max Realty.

-------------------------------------------------------------------------------

There are reasons why I think my two sentences are correct. In (1a), "have been pranked" and "am working" are both present tense, meaning that from day 1 of my employment until now, there have been quite a few times done me. Furthermore, "am working" indicates that I am still working there. Your colleagues may continue to prank me in the future. In (1b), the past tense indicates that I am not working there anymore. During my previous employment, a few pranks were done on me.

I think (1c) is wrong. Like I said, "was working" means you are no longer working there, which does not fit well with the present perfect "have been pranked", which suggests that your colleagues may continue to prank you in the future. In other words, they may continue to do so even when you are no longer there. This does not make sense.

------------------------------------------------------------------------------------------------

What is your opinion? Thank you very much for all your time and help.