If you are affected, you can order a free replacement online, just log in to this site and follow the instructions:
Of course you can also call Microsoft.
See below what the recalled wires look like (excluding the charging head on the right), if you have a newer one you don’t need to replace it. Newer cords include strain relief improvements where the AC cord joins the ends of the plug, which should further reduce the possibility of damage if the cord is repeatedly twisted too tightly.
No need to send old cables to Microsoft or provide proof of damage, just be aware that there is only one AC power cord per Surface Pro device, if you have more than one device, you need to install a separate power cable for each device Order.
Microsoft also has a plan for business users who may be affected by this, as well as users who may place large orders, in which case there is also no charge.
Specific to Surface Pro 3 devices, only customers who purchased Surface Pro 3 devices before March 15, 2015 are eligible. Newer Surface Pro 3 devices already have a new style of AC power cord.
If you have any of these affected devices, Microsoft also recommends discontinuing your AC cord during the free replacement process.