Ping spiking after switching to Unlimited

[#1]

Hi all.
We have been on the Pro package for a month, but read some opinions on it that suggested that the ping on Pro and the ping on the Unlimited packages were fairly similar. Due to this we decided that we'd switch to Unlimited as 15gig is a bit small for us when we like to download DLC from xbox live. The switch happened two days ago and we've gone from a solid 30ms ping (tested by pinging bbc.co.uk) to having it spike to over 100ms fairly regularly (i.e, 30, 34, 32, 56, 100 and back down again).
Our question is, does anyone know if the ping instability present when first switching to plusnet also occurs if you switch packages and this is what we're experiencing? Also we've left the router settings at what they were on when we were on Pro, I take it there's no changes needing to be make for Unlimited?

[#2]

Hiya,
There won't be any need to change settings as a result of changing product and to be honest with you, as long as we're identifying the trasffic properly, ping should be similar.
Looking at your line, interleaving is turned on which will account for some of the latency, so we could turn this off with the previso that it could cause some instability, but we can turn it back on again within a working day should that happen.

[#3]

Thanks a lot for the swift response 😃 I've put a ticket in to get interleaving switched off, we'll see how we go.

[#4]

Cheers
I've placed the order, but because of the long weekend, it won't complete until Tuesday.

[#5]

Figured that would be the case. Thanks for the help 😃