cannot send/receive sms or multimedia texts

Try to contact Fiiz by:
CHAT
Go on this page https://fizz.ca/en/faq/resolving-issues, if you are not connect login
Wait 15 seconds for the bubble icon to appear at the bottom right of the browser and click on the icon.
FACEBOOK
You can also send a message by Facebook
https://facebook.com/fizzca and click send a message (this is a bit slower)

You can try this: https://communaute.fizz.ca/questions/1935428-mms-problem-...

Can you give the exact model
If you have the LG K210 seems to be compatible, therefore, the problem is not the model

Did you input APN parametera by yourself or you used config files given by Fizz. If not try both.
Look also to this page
You should be able to send or receive MMS check your APN settings https://fizz.ca/en/faq/what-are-fizz-network-settings-apn

As said by Sergio, you probably need to enter the APN Setting manually. Some older phone doesn't receive config messages but still, support Fizz by entering the config manually. That's what I did on my wife phone, a Galaxy Grand Prime, works like a charm.

This is normal by fizz