Hi @Agaton McManaman! Welcome here. I'm sorry that your sim-card stopped working. Do I understand correctly that you already received a new SIM-card, since you needed to activate SIM card, or not?
I would like to check what is going on. Can you please enter your subscription details in your profile and let us know when you did so? Postal code, house number, customer number and the last 3 digits of the bank account number known to us is sufficient. 

My subscription details are in this profile

Edit: I am not finding a box to enter anything abot bank account number.

To clarify: I did not receive a new SIM card, I am still using the same old one. I just extended the subscription on the same number. Calling works without problems on this old SIM card. I just checked if I could activate it again to see if this would solve the problem.

Hi @bernaeraslan. Could you please turn your phone off and on again? The option wasn't turned on. It should work now. 

It is working now. It was not working for four days. What was the reason for this? I have complaints

Not really sure, I just did a quick reset of the connection and could see that everything was back online. I'm sorry for the inconvenience. 

Please how do I restart my phone after I turn it completely off. There are four number digit I need to use but I don't know it?

Hello @Daniel zz 

Is it asking for the sim pincode?

You should have received documentation with the simcard on which it is mentioned, but if you changed the pincode that is not correct anymore.

If you don't have that anymore you could try 0000 or 1234

After three times entering the wrong pincode it will ask for the pukcode, you should also have received that with the simcard.

You also can get it through this website after filling in the details: https://www.kpn.com/service/mobiel/pukcode.htm

Probably you need the second option: https://www.kpn.com/service/mobiel/pukcode/pukcode-opvragen.htm

If it's greyed out and hard to read on the website click on it to make it visible.

After entering the pukcode you have to fill in a new pincode on your mobile.

I have cellular error and my phone completely stopped working? Could someone pls urgently help?

What do you see exactly on your screen? Which error? 

Hi! I have the same problem. I arrived France just an hour ago and my internet is not working. I am stuck in train station to use the wifi here. I tried calling kpn and called 2 numbers but I couldn't reach one and the other was not English and my Dutch is not good. I need immediate help.

I got this message and translated it that I can use my internet but WHY can't I?

Hi @Ezgi Erdogan, welcome on our forum. First off please check if Roaming is ON. After that you should try selecting other available networks, you can do this manually in the settings of your phone. 

Hi! After half a day, and with the help of a Dutch lady, she helped me to be called back and the person there was very helpful. Thank you.

P.s. Please add English to your callcenter at least. I'm sure you have many subscribers who don't know Dutch yet^^

Thank you

I'm glad it works now. Thank you for the suggestion regarding the English option, I will pass it on.