Around 100 workers in the Unite union struck for 48 hours at the DHL facility at London Heathrow airport on Thursday and Friday of last week.
They are employed by Menzies World Cargo but are paid less than some other workers doing the same job.
They struck against a two-year pay freeze.
UPS walkout over ‘bullying’ bosses
Around 120 drivers, packers and loaders struck at UPS parcel depot in Camden, central London, on Friday of last week.
The Unite union members are angry over allegations of bullying, and workloads they say are unreasonable.
Unite warned that it could call further action in the run-up to Christmas.