I myself am familiar with DLC and have found them to be understanding once the situation has been fully explained.
Of course, like any call centre there are a few bad eggs but most people there are reasonable.
They have guidelines to work to like we all do in our jobs and most importantly they have a licence they could lose if they behave inappropriately.
The current climate seems to have had an impact on this company and I for one have been dealt with decently by several people there. I think they have finally realised that there is no use in this day and age in pushing too hard for something unrealistic.