I wouldn't pay unless the files are EXTREMELY valuable.  1.5 btc is almost a thousand dollars.  In the worst case where you cannot decrypt those files you could contact the laptop mfg and reload the system from scratch.  Probably an available download for free even and then forensically wipe the disk before installing the new system.  It would only take a few hours to have a fresh new system disk.  If important files are backed up on a flash or external drive those can be copied back easily.  Do NOT connect any removable media to that infected computer.  This is what I do, so if you need a few steps in the process to be outlined, please ask here.