Service Interuptions: still not resolved after months

How do I log a formal complaint of have an ongoing issue escalated.  I’m experiencing CONSTANT service interruptions where my all services (internet, tv, wifi) lose connection and I either have to wait 10-20 minutes for everything to start working on its own, or I have to physically reset the router. This has been happening for nearly 2 months.

A technician was sent out 2 weeks ago, the router was swapped out (firmware not updating) and the problem persists. Subsequent attempt to get this resolved ended with an Agent indicating that a newer model of the router would be provided. I have had no communication from KPN AT ALL regarding this since. I can therefore reasonably assume that I have been lied to,

I called the customer service center AGAIN this morning as I have experience 2 interruptions thus far today.  The agent’s response was reset your fiber box, and keep an eye if it happens again, and call us back.  When I asked for an update on the new router that was promised I received no update, not even a confirmation that this agreement is on record. 

THIS IS UNACCEPTABLE and unbelievably bad customer service.  I need information on how to escalate the matter since it is clearly NOT a priority to resolve this matter, and hopefully someone more senior that a call center agent can get this matter investigated and resolved once and for all.