An operator in Algeria, found that when attempting to put wells on production, the lock mandrels were found to be stuck in the nipple profile. All slickline attempts failed to retrieve the mandrel. When coil tubing was deployed, one plug remained stuck in its nipple, while the second one came off its seat only to get stuck inside a Side Pocket Mandrel, about 25m shallower. The sequence of pulling and jarring resulted in both fish necks coming apart, thus rendering all subsequent fishing attempts impossible. Therefore, a decision was made to attempt to mill the mandrels using the new e-line milling technology. Another challenge was that the 2.562″ and 2. 75″ ID mandrels were made of 13 Super Chrome, and there was limited experience milling these types of completion components. Also, due to a rush mobilization, there was no time to execute a SIT. The solution presented consisted of milling first the mandrel outer sleeve, then milling the inner sleeve from the plug body which will cause the mandrel anchoring system to collapse. Special 2.2" and 2.375" milling bits were manufactured and sent to location. The e-line tractor conveyed the toolstring to target depth where the e-line milling tool was activated and milled through the mandrel sleeves, releasing the anchors. On the first well, the 2.562″ mandrel sleeves were removed using a 2.2″ bit, while the sleeves on the 2.75″ plug were milled using a 2. 375″ bit. With the sleeves removed, slickline ran in hole with a combination of magnets and scratchers (wire brush) of different sizes and fished the remainder of the plug. With full bore access on both wells, and after performing a clean-out operation, the operator could increase the gas production by 100%. This was the first time the e-line milling toolstring was used to mill and remove a lock mandrel. This paper will review a new application of e-line milling technology to remove heavy duty lock mandrels in order to allow wellbore access and improve the production.