Help, cannot change reference of Renderer.material

I have fought with this for some time and done lots of googling yet i have failed to succeed in this. In my game the player can create alot of objects at runtime and i want him to be able to change what color the created objects are. Some could be blue, some red, etc. and i had it working in a way that it always created new instance of material, which later on now caused me quite a bottleneck on dynamic batching.

I have created a material/color storage class system and am able to save them there succesfully but i can't apply them to the objects Renderer.sharedMaterial for some reason (it doesn't change anything) and if i use Renderer.material it creates new instance. Most likely the problem here is my lack of understanding how the materials/renderer works. Any help appreciated.

Heres the code im running:

 private void CreateObject()
     {
         if (!GetInput.cursorOverHud)
         {
             foreach (Transform t in Placeholders)
             {
                 Transform o = UnityEngine.Object.Instantiate(t, t.position, t.rotation) as Transform;
 
                 foreach (Collider col in o.GetComponents<Collider>())
                     col.isTrigger = false;
 
                 o.gameObject.layer = 9;
                 o.GetComponent<Rigidbody>().isKinematic = false;
                 o.GetComponent<DynamicObject>().Set();
                 Renderer oRend = o.GetComponent<Renderer>();
                 Renderer tRend = t.GetComponent<Renderer>();
 
                 for (int i = 0; i < oRend.sharedMaterials.Length; i++)
                 {    
                     // Nothing happens
                     oRend.sharedMaterials[i] = MatColStorage.GetMaterial(tRend, tRend.sharedMaterials[i].color, i);//mat[i];//tRend.sharedMaterials[i];
                     // But if i were to assign into 'oRend.materials[i]' i get lots of instantiated materials
                 }
             }
         }
     }

And the storage class:

 public static class MatColStorage
 { 
     private class MaterialColor
     {
         private Material mat;
         private Color col;
 
         public Material material
         {
             get
             {
                 return mat;
             }
         }
         public Color color
         {
             get
             {
                 return col;
             }
         }
 
         public MaterialColor(Material material, Color color)
         {
             mat = material;
             mat.color = color;
             col = color;
         }
     }
     private static List<MaterialColor> instantiatedMaterials = new List<MaterialColor>();
 
     public static Material GetMaterial(Renderer rend, Color col, int whichMat)
     {
         foreach(MaterialColor matcol in instantiatedMaterials)
         {
             if(matcol.color == col)
             {
                 return matcol.material;
             }
         }
 
         Material refMat = new Material(rend.materials[whichMat]);
         refMat.color = col;
         instantiatedMaterials.Add(new MaterialColor(refMat, col));
         
         return instantiatedMaterials[instantiatedMaterials.Count - 1].material;
     }
 }