Well all depends on the prices the refineries set. Yes some garages cashed in by upping their margin but if they are lets say buying diesel in for £1.35 per litre they will have to charge more than that for it to make a profit. Before of course they were buying it at £1.27 and wacked their prices up to £1.39 to cash in.
As of yesterday the average uk fuel pump price for diesel was £141.47 and is still going up everyday. Compared with £1.12 on the 2nd June.
Wholesale prices from the refinery continues to rise every day as well. There might be a bit of play in forecourt prices but for now these prices are here to stay.
We are almost at the highest fuel prices for 8 years and I dont think its stopped going up yet.
https://www.racfoundation.org/data/wholesale-fuel-prices-v-pump-prices-data