Hm Digital PH meter calibration HELP!!!

[LEDhead]

Just received a new PH pen because I felt my older one was a bit worn and probably not calibrating properly so I received the new one yesterday and immediately calibrated it to 7.0 with the required solution, simple... check my solution that I’ve already calibrated to 6.0 with my old pen and it’s showing 7.5ish on the new pen, double even triple check the calibration at it’s dead nuts 7.0 and the older one is also calibrated to 7.0 so I’m at a loss both pens I know are cheap so Black Friday I’m swooping up a Hanna meter.
think I should write the HM company and see what I can do about a refund or just call it a loss?
Pics in fresh RO with fresh filters, new pen first older pen second.

 

[JSH1973]

I have just started to have issues with first one PH pen and then the other as well, one I got refunded for one and the other one is being replaced, thankfully I can get by with the one that still ''almost work'' as I know my nutrient mix well enough, besides the replacement PH Pen I also have another upgraded pen coming and I treated myself to a Blue lab EC tester which will get the PH equivalent as a partner soon, buy cheap buy twice no more... My plants deserve better

 

[LEDhead]

I have just started to have issues with first one PH pen and then the other as well, one I got refunded for one and the other one is being replaced, thankfully I can get by with the one that still ''almost work'' as I know my nutrient mix well enough, besides the replacement PH Pen I also have another upgraded pen coming and I treated myself to a Blue lab EC tester which will get the PH equivalent as a partner soon, buy cheap buy twice no more... My plants deserve better

40% off at growgen so I’ll be getting a nice one then