Whatsapp verification without number
I recently tried to open my Whatsapp application, and was surprised with the verification screen, I was supposed to enter my telephone number, which wouldn't be a problem if I wouldn't have a new contract with a different number now. I used Whatsapp for months after I changed my contract (and number) without any problems, so therefore I never used the Whatsapp function to move your profile to a new number. Now, if I enter my new number, it brings me to the "create profile" site, and if I do create a profile here and proceed, none of my chats etc. show up, which is not a wonder as it is a new profile. So I tried reinstalling the app, I have iCloud backups from my chats so I wanted to use these, this didn't work, so I thought I might reset my phone completely and load my latest backup from when it worked. I did this, and opened the app, it showed my old profile as I knew it for around 1-2 seconds, before viewing the message "blblablabblabla... Please verificate your number..." So naturally I asked the Whatsapp support team about this, but at first they sent me one of these automated "please check that the following settings and instructions are met" mails, so I went on and wrote them, that none of these helped, and that I needed "real" help. They haven't answered me yet, they probably will in the next days, but I'd like to solve this before that, plus I'm not quite sure they can help me either.
Here is some information that could help
iPhone 5S on iOS 9.3.2
I still have the sim-card from my old contract (but the contract is cancelled)
The solutions I thought off are:
When I reset my phone, I had these 2 seconds where my Whatsapp app was working, if I had more time I should be able to move my profile to my new number. Is there a way to disable in-app notifications? My iPhone isn't jailbroken, but if there was a Cydia tweak which allows this, I would also jailbreak my phone.
Extract the chats from my backup using a program like ifunbox or something, and just push it into the folder where Whatsapp puts the chats, as this is not the intended way to do it, I think I could run into some compatibility problems this way.
The chats are extremely important to me, as they include some of the most important conversations I ever held, and they represent a huge chunk of myself, as such I would be extremely sad if I wouldn't get them back one way or another.
If this was posted a wrong place, feel free to move it around, this is my first post here.
If you need any additional information, please ask.
I thank you for your time and possibly your solution to this dilemma.