Incorrect 'unlatching' code entered too many times

[AlanEBrown]

My elderly parents have an old O2 Samsung J3 and when the 02 contract ended towards the end of last year, they got a Vodafone SIM not realising the phone was locked to 02!  When they put the SIM in and the phone asked for the unlatching/network unlock code, they kept inputting the screen lock PIN which has now hard-locked the phone by the looks of things.

I have an old Vodafone handset and the Vodafone SIM works OK in there so presume there's something I need to do on the O2 Samsung J3 to get it to unlock and 'read' the Vodafone SIM?

I did get a couple of Network PUK codes from O2 already but those codes don't seem to work on the screen where it says to enter them (i.e. as soon as I boot up the phone).

Any ideas anyone?  Saw a reference to @Martin-O2 in another thread who may be a good source of information for this sort of thing?

Thanks in advance

[MI5]

@AlanEBrown 

You need the MCK code which 

@Martin-O2 

@LukasB or 

@TheresaV can help you with.

[LukasB]

Hey @AlanEBrown I will send you a private message as I need some information and then will request the MCK for you.