Crown Thinning - is often the best solution where a tree has grown too dense and vigorous for a garden or site. We reduce the overall density of the crown by removing dead and crossing branches as well as secondary branches. This leaves the main branch structure of the tree intact and minimises the amount of vigorous 'regrowth' seen after pruning. The tree retains its natural shape, yet allows far more light through the canopy and onto the ground. We can thin the whole tree crown or just specific areas.

Crown Reduction - is the best solution where the tree's crown is simply too large, but it is important to retain a natural tree 'shape'. We reduce the height and spread of the crown by pruning branches back to a suitable union to create a balanced tree shape and outline. The amount by which we reduce the tree is best described as a percentage (for example, "reduce the crown by 20%"). This Tecnique is only availabe for smaller tree species under 25 ft.

Have you ever seen one of those trees that looks like someone gave it a crew cut ?  Pollard is a method of pruning to control a tree’s size or maybe after the tree is damaged in a storm.  It’s also called “hat-racking” or “tipping.”
Pollard Topping Harm Trees ?
Well, Tree/s rely on their leaves in order to go through the process of photosynthesis and create food for themselves.
Topped trees quickly develop lots of new growth,  branches grow as an effort by the tree to create more leaves and more food as quickly as possible.  Growing small shoots that are weakly attached to vessels just under the bark of the tree and are highly susceptible to damage from wind and storms. These new branches will always be weakly attahed to the tree and that can cause future damage as the branches grow larger.
Another tragic thing about pollard topping is it shortens the life of the tree. The tree is not able to create a sustainable strategy for survival and food production in the long run causing its own demise

 Ask Them to DO NOT use spikes while climbing your trees to Prune or Trim them. SRT (Single Rope Technique) a Spikeless tree trimming and pruning technique. That’s the proper way to do it. Its non-invasive preserving the health and life of your trees.
The use of spikes can result in long-term damage to your trees. Tree Climbing Spikes where made for Tree removal and Pole climbing so beware if one is using Climbing Spikes to Trim or Prune your valuable Trees

These listed issues occur due to the damage from Climbing Spikes;
*Bacterial Infections
*Shoot growth
*Fungi Infections
*Disease Transfer from dirty spikes
*Insect Infestation from wounds left from spikes
Tree trimming using spikes (gaffs) damage the tree’s vascular system right below the bark. A tree in optimal health will be damaged by climbing spikes (gaffs) holes on a healthy tree. One very important question any homeowner should ask any tree company from whom they’re getting a quote: “Will you use spikes when you trim or prune my trees?”