We know a great organisation called Mobile Refugee Support who provide on-the-ground support to refugees stranded in Northern France.
One quite unique thing they provide is communication support. Communication devices, power and connectivity is vital. It allows contacting loved ones thousands of miles away or family at an intended destination. In addition, even basic devices can provide e.g. GPS which can be lifesaving.
MRS fix phones and power banks and provide access to charging stations. They will also take apart old phones for parts, and even repurpose lithium ion batteries to build new powerbanks.
If you have old phones, power banks, charging cables (and other things - more info), they will likely be able to take and use them to help. You can drop them off or post them - contact MRS via Facebook: https://www.facebook.com/MobileRefugeeSupport/