there are few to choose from in LED.
The main one used to be Pulkovo Aircraft Services (PAS)- nice guys, I worked with them for a long time including biz aircraft handling etc. Always good service etc.
It looks like PAS is being pushed away by JETPORT handling that belongs to Rusaero and who offer the best rates at the moment. I dealt with them a couple of times, handling a F100 and MD83... They did the job, but it was far from ideal. They concentrate more on aircraft handling rather than on pax handling and I had to subcontract a local rep who was dealing with my passengers.
There is also a handling company called Virtrans - never used them but they were recommended to me quite a few times.
Remember that both PAS and JETPORT will be asking for pre payment based on proforma invoice and you might get charged extra afterwards.
Be careful and read through invoices thoroughly - there are always "mistakes" and "typos" that might increase the final amount.
All payments go via Rusaero.
There is also an alternative to all that - you can use Streamline OPS Handling for your permits and handling set up. They have their own rep in LED - Spanish guy I think... he's a bit of a "one man show" but does the job...
hope that all makes sense and helps.