While his father [was/has been] shopping

I have made up the similar sentences below.

(1) When I have time, I go the apartment upstairs and look after my friend's son, John. I have been pranked by him at least twice while his father has been shopping at ABC Supermarket.

(2) When I have time, I go the apartment upstairs and look after my friend's son, John. I have been pranked by him at least twice while his father was shopping at ABC Supermarket.

Some of my non-native English speaking friends think "have been shopping" is correct because it agrees with "have been pranked". However, Some of my other friends think "was shopping" sounds better because his father was out shopping when the pranks were done on you. The rest of my friends think both are correct.

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