Found a great article on stack overflow for increasing Virtual Box VMDK Storage Size. It's by converting to another type VDI and then converting back to VMDK
VBoxManage clonehd "source.vmdk" "cloned.vdi" --format vdi
VBoxManage modifyhd "cloned.vdi" --resize 51200
VBoxManage clonehd "cloned.vdi" "resized.vmdk" --format vmdk