I have a VM running Ubuntu and previously resized the disk space from 20G to 40G following this excellent guide [joomlaworks.net].

Several months later I am now trying to resize again- resized the VM to 80G, but I get the following message when trying to create a new partition in fdisk:
All primary partitions are in use
Adding logical partition 6
No free sectors available

Here is the list of partitions:
Disk /dev/sda: 85.8 GB, 85899345920 bytes
255 heads, 63 sectors/track, 10443 cylinders, total 167772160 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0009b170

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 499711 248832 83 Linux
/dev/sda2 501758 41940991 20719617 5 Extended
/dev/sda3 41940992 83886079 20972544 8e Linux LVM
/dev/sda4 499712 501757 1023 83 Linux
/dev/sda5 501760 41940991 20972544 8e Linux LVM

I'm not an Ubuntu guru and pretty much stumped at this point.