Is my pH probe broken? Too strange data

[progman]

I checked the ocean water by my pH sensor. It shows 8.5 pH. Unbelievable!
My water shows 8.7-88 pH. Two time unbelievable!

I calibrated the sensor. I used standart 7pH and 9 pH calibration liquids.
nothing changed

But the sensor shows 6.75pH for 7pH calibration liquid!!!
And 9.0 pH for 9pH calibration liquid

The chemical test shows 8.1pH for our ocean water and 8.3 pH for my water in the tank.

How to fix the bug of my pH sensor?

[Vinny]

How old is the pH probe?
How old is the calibration fluid?

Perhaps the pH7 calibration fluid is contaminated causing the lower range reading to be off.

[progman]

The probe is 3 years old
The liquids have valid date until 01/2019

I was buying 3 different calibration liquids. ( 3 different date ).
May be the probe broken ?

[Vinny]

At 3 years old, it would be best to replace the probe.

As probes get older (1 yr+), they will require more frequent calibration to maintain accurate readings.

[progman]

I ordered new one pH probe and calibration liquids.
Today I have got it.
After calibration a computer shows 9.00 pH for 9pH calibration liquid and 7.35pH for 7pH calibration liquid.
And 8.75 pH for my water in the tank ( Chemical test shows 8.1-8.2 pH )

PS I spent 150 eur for probe, liquids and delivery to my country. Thank you for the useless advice to switch to new sensor.
And maybe I should spent more money for new profilux 4 ? )))))