Singleton Class Property

This is my code in Singleton

namespace WpfCloud
{
public class WordCloudHelper
{
private static WordCloudHelper _instance;

ServiceSoapClient _service; //for cloud services

protected WordCloudHelper()
{
_words = new List<string>();
}

public static WordCloudHelper Instance
{
get
{
if (_instance == null)
{
_instance = new WordCloudHelper();
}
return _instance;
}
}

private List<string> _words;
private String _text;

public void EnterWordsInCloud(String text)
{
_service = new iDigitalService.ServiceSoapClient();

WordCloud cloud = _service.getLatestWordCloud();
text = _text.ToUpper();

int identity = cloud.cloudID;
_service.addWordToCloud(identity, text);
}

public List<string> GetWordCloud(String text)
{
if (text.Length > 0)
{
_words.Clear();

WordCloud cloud = _service.getLatestWordCloud();
PlayWord[] words = cloud.words;

Dictionary<string, int=""> arrange = new Dictionary<string, int="">();

foreach (PlayWord word in words)
{
text = word.word;
int number = word.count;

arrange.Add(text, number);
arrange.Remove("BITCH"); //profanity list

if (!arrange.ContainsKey(text))
{
arrange.Add(text, 0);
}

else if (text.Length > 11)
{
arrange.Remove(text);
}

else
{
int count = arrange[text];
arrange[text] = count + 1;
}
}

var sortDict = from entry in arrange orderby entry.Value descending select entry;

//var result = arrange.Select(element => element.Value > 50);

//arrange = arrange.OrderBy(k => k.Key).ToDictionary(k => k.Key, k => k.Value);

List<string> final = new List<string>();
foreach (KeyValuePair<string, int=""> entry in sortDict)
final.Add(entry.Key);
final.RemoveAt(2);

List<string> duplicate = final.ToList();

string check = textbox1.Text;

if (duplicate.Contains(check) == true)
{
int remove = Math.Max(0, final.Count - 25);
final.RemoveRange(0, remove);

int delete = Math.Max(0, duplicate.Count - 5);
duplicate.RemoveRange(5, delete);

duplicate.Add(check);

duplicate.AddRange(final);
}

else
{
int remove = Math.Max(0, final.Count - 25);
final.RemoveRange(0, remove);

int delete = Math.Max(0, duplicate.Count - 5);
duplicate.RemoveRange(5, delete);

duplicate.AddRange(final);
}

_words = duplicate.Distinct().ToList();

}

else if (_words.Count == 0)
{
WordCloud cloud = _service.getLatestWordCloud();
string header = cloud.header;
PlayWord[] words = cloud.words;

Dictionary<string, int=""> d = new Dictionary<string, int="">();

foreach (PlayWord word in words)
{
text = word.word;
int number = word.count;

d.Add(text, number);
d.Remove("BITCH"); //profanity