Your ISP provides VPN services between your cpe and its server , before other things, you may want to ask if it allows also the bonding of the VPNs, if yes you might obtain better performances, otherwise you will add only overload on the local loop (different it would be if you were talking about a site to site VPN, where both end points are under your control, and you want protect your data while traversing the internet, in this case the overhead is tolerable).
Regards