That sounds a bit unreasonable to me!
Provided you’re sure that they can support it (correct firmware version, etc), I don’t see why they shouldn’t just sell you the necessary activiation codes.
(remember that WIP was only released fairly late in the life of the M1306B)
A client of mine had a similar requirement, and there was no problem with that.
Can you escalate the issue with the Distributor?
Can you contact Wavecom direct?
You can’t activate the plugin without the necessary activation code - which is tied to the IMEI, and must be paid for.
Do you really need the internet plugin?
The plugin is only needed for the higher level protocols - HTTP, FTP, SMTP, etc - if you can just use “raw” TCP or UDP sockets, then you don’t need the plugin.